 /*******************************************************************************
  * Copyright (c) 2006, 2007 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.core.internal.databinding.observable.tree;

 /**
  * @since 1.1
  *
  */
 public abstract class TreeDiffNode {

     /**
      *
      */
     public final static int NO_CHANGE = 0x00;

     /**
      *
      */
     public final static int ADDED = 0x01;

     /**
      *
      */
     public final static int REMOVED = 0x02;

     /**
      *
      */
     public final static int REPLACED = 0x03;

     /**
      *
      */
     public static final TreeDiffNode[] NO_CHILDREN = new TreeDiffNode[0];

     /**
      *
      */
     public static final int INDEX_UNKNOWN = -1;

     /**
      * @return the change type
      */
     public abstract int getChangeType();

     /**
      * @return the element that was removed, or the replaced element
      */
     public abstract Object getOldElement();

     /**
      * @return the element that was not changed, added, or the replacement
      * element
      */
     public abstract Object getNewElement();

     /**
      * @return the index at which the element was added, removed, or replaced
      */
     public abstract int getIndex();

     /**
      * Returns the child tree diff objects that describe changes to children. If
      * the change type is REMOVED, there will be no children.
      *
      * @return the nodes representing changes to children
      */
     public abstract TreeDiffNode[] getChildren();

     protected void doAccept(TreeDiffVisitor visitor, TreePath parentPath) {
         TreePath currentPath = parentPath.createChildPath(getNewElement());
         boolean recurse = visitor.visit(this, currentPath);
         if (recurse) {
             TreeDiffNode[] children = getChildren();
             for (int i = 0; i < children.length; i++) {
                 TreeDiffNode child = children[i];
                 child.doAccept(visitor, currentPath);
             }
         }
     }

 }

